Liquid skimming device



6 L. w. LEFKE ETAL LIQUID SKIMMING DEVICE Filed Sept. 14, 1966 E f FN 8 M i Y A A v a A M 1 A 9 3 w 571i M PATENT ATTORNEY United States Patent 3,338,414 LIQUID SKIMMING DEVICE Louis W. Lefke, Morris Plains, and William H. Lang,

Cranford, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Sept. 14, 1966, Ser. No. 579,267 6 Claims. (Cl. 210-179) This invention relates to an improved apparatus for skimming a floating contaminant from the surface of the liquid upon which it is floating. The present invention is particularly applicable in the area of controlling oil refinery pollution.

While skimming apparatuses in general are known to the art, many problems are experienced with their use. These problems include the fact that quite often large quantities of water are collected along with the oil to be skimmed thus greatly reducing the effectiveness of the separation. Weather conditions also often adversely affect the degree of separation afforded by those devices now known in the art. For example, cold weather causes the heavier fraction of the floating oil to congeal in large masses which are diflic-ult to collect from separator pickup surfaces. Furthermore, this semisolid oil often causes clogging problems in collection troughs and associated piping. Conversely in warm weather the oil spreads out in a thin surface coating the water and making elfective separation difiicult. In both cases, excessive amounts of unwanted Water are collected.

Accordingly, it is a specific object of the present invention to maximize oil recovery while minimizing water pickup.

A further object of the invention is to eliminate detrimental temperature eifects on oil viscosity by providing means for varying and controlling the temperature of the separator pickup surfaces.

According to the teachings of the instant invention, it has been found possible to achieve a highly effective oil film separation by means of a large oil-attractive surface which is rotated through the oil-water interface.

A fuller understanding of the invention and further objects may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIG. 1 shows an isometric drawing of the new and improved oil skimming device.

FIG. 2 shows a sectional view taken along line 2-2 of FIG. 1.

FIG. 3 shows a view of the rotatable pickup surface taken along the line 33 of FIG. 2.

Referring to FIGURE 1 in detail, the pickup mechanism of the instant invention shown generally at 4 is rotatably mounted on support channel 1 so that it may be revolved through the interface of the separated free-oil layer 11, and the waste water layer 8 therebelow. Pickup portion 4 is provided with a highly extended pickup surface indicated schematically at 5. This pickup surface is of generally serrated configuration. As a key feature of the instant invention, extended pickup surface is to preferentially attract oil from the oil-water mixture through which the surface revolves. Consequently, the surface is to be hydrophobic in nature and to this end it may 'be conveniently made of a suitable hydrophobic material such as polished aluminum, polished steel, or an oil wettable plastic. Drum portion 4 is rotated through the oil-water interface by means of an automatic variable speed drive indicated schematically at 10. As hydrophobic surface 5 passes through the interface of the free-oil and Water it preferentially picks up the oil. It is to be appreciated that optimum oil pickup is dependent on the depth of penetration exhibited by the serrations of extended pickup surface 5.

3,338,414 Patented Aug. 29, 1967 Referring to FIG. 3, maximum recovery is achieved when the interior roots or apices 14, of the serrations forming pickup surface 5 are located at or about the oilwater interface 9. When the penetration is deeper than this, excessive washing takes place as the serrations pass through the water and the oil pickup becomes less eflicient. Similarly when the penetration is substantially less than that indicated above as being optimum the hydrophobic pickup area 5 is not being utilized to its full extent and this also reduces the efliciency of separation.

Returning to FIG. 1, drum 4 continues to rotate and the oil is removed from serrated pickup surface 5 by a squeegee or doctor blade shown schematically at 6. This blade may be made of rubber or other resilient material and also has a serrated configuration so that it may matingly engage and make full contact over the entire area of pickup surface 5. From doctor blade 6, the removed oil flows into a collection trough 7 from which it is conducted from the system.

It is seen that drum 4 is rotated in the direction of flow of the oil-water stream. This aids the separation by pulling the free oil into the large contact area afforded by the serrated surface. This method of operation tends to decrease surface turbulance and thus aids separation. It is to be appreciated, however, that drum 4 will also perform its intended function while slowly being moved across the water surface. Oil-water mixtures are frequently collected in separator ponds and it is in this environment that the latter method of operation may be suitably employed.

An additional feature of the instant invention is the ability to heat or cool the oil attracting serrated pickup surface 5.

Referring to FIG. 2 it is seen that drum 4 is provided with internal heat transfer coils or the like indicated schematically at 12. Variable heat pump 16, supplies heat or cold to coils 12 whereby the temperature of pickup surface 5 may be controlled and maintained at a given optimized level. It is to be appreciated that the heating and cooling of pickup surface 5 may also be accomplished by any conventional means such as steam, electricity and a refrigeration unit. As previously indicated, this versatility in the control of the pickup surface temperature is essential for optimum efficient free-oil removal.

A further advantage of the instant invention is that attendant facilities such as slop oil treating tanks, pumps and steam requirements generally required for oil-water separators are reduced in size and quantity because of the greatly reduced amount of water collected. Consequently, operating costs of pollution control are greatly reduced by using the instant invention and effluent water cleanliness is greatly improved.

Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example and that obviously changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed. It is also to be appreciated that the invention is not limited to oil-water separations but may in fact be used to effect the separation of other immiscible liquids.

What is claimed is:

1. In a skimming apparatus for liquid separation of a top immiscible liquid layer from a bottom liquid layer the combination comprising a stream of liquid having a top immiscible layer and a bottom immiscible layer and an interface therebetween, means for guiding said stream, a drum having a serrated hydrophobic pickup surface, mounting means for rotatably mounting said drum, whereby the axis of rotation of said drum is so located above said stream such that the roots of the serrations of said hydrophobic pickup surface lie on said interface when said serrations, as viewed in cross-section, are at their limit of downward travel, means for removing liquid from the hydrophobic surface of said drum, said removing means including a squeegee blade making continuous contact with the surface of said hydrophobic pickup surface, and means for varying the rate of rotation of said drum.

' 2. The apparatus of claim 1 wherein said combination further includes temperature control means for regulating and controlling the temperature of said hydrophobic pickup surface 3. The apparatus of claim 2 wherein said temperature control means includes a heat pump whereby said hydrophobic pickup surface may be cooled.

4. The apparatus of claim 1 wherein the material for the hydrophobic surface is selected from the group consisting of polished aluminum, polished steel and a smooth oil-wettable plastic.

5. In an apparatus for removing floating free-oil from a water surface the combination comprising a stream of water, a layer of free-oil on the surface of said water thereby defining an interface between said water and said free-oil, a trough means for guiding said stream, a drum having a hydrophobic pickup urface of serrated configuration, means for rotatably mounting said drum on said trough means whereby the axis of rotation of said drum is so located above said stream such that the roots of the serrations of said hydrophobic pickup surface lie on said interface when said serrations, as viewed in cross-section, are at their limit of downward travel, means for varying the speed of rotation of said drum, means for regulating and controlling the temperature of said hydrophobic ickup surface, means for removing said oil from said pickup surface, said last means including a squeegee blade of serrated configuration making continuous contact with the rotating pickup surface of said drum, said squeegee blade located on the downwardly rotating side of said drum, and collection trough means contiguous with said squeegee blade for collecting said oil from said blade.

6. The apparatus of claim 5 wherein the material for the hydrophobic surface is selected from the group consisting of polished aluminum, polished steel, and a smooth oil wettable plastic whereby said surface preferentially picks up said free-oil.

References Cited UNITED STATES PATENTS 1,573,085 2/1926 Meiani 210-242 1,611,095 12/1926 Wilhelm 210-178 X 1,860,819 5/1932 Schamberger 210-523 2,910,838 11/1959 Ewing 62-324 X 2,950,607 8/1960 Fries 62-324 3,127,930 4/1964 Tenniswood 62-324 3,146,192 8/1964 McClintock 210-525 X 3,245,539 4/1966 Earle 210-523 X REUBEN FRIEDMAN, Primary Examiner.

J. DECESARE, Assistant Examiner. 

1. IN A SKIMMING APPARATUS FOR LIQUID SEPARATION OF A TOP IMMISCIBLE LIQUID LAYER FROM A BOTTOM LIQUID LAYER THE COMBINATION COMPRISING A STREAM OF LIQUID HAVING A TOP IMMISCIBLE LAYER AND A BOTTOM IMMISCIBLE LAYER AND AN INTERFACE THEREBETWEEN, MEANS FOR GUIDING SAID STREAM, A DRUM HAVING A SERRATED HYDROPHOBIC PICKUP SURFACE, MOUNTING MEANS FOR RETATABLY MOUNTING SAID DRUM, WHEREBY THE AXIS OF ROTATION OF SAID DRUM IS SO LOCATED ABOVE SAID STREAM SUCH THAT THE ROOTS OF THE SERRATIONS OF SAID HYDROPHOBIC PICKUP SURFACE LIE ON SAID INTERFACE WHEN SAID SERRATIONS, AS VIEWED IN CROSS-SECTION, ARE AT THEIR LIMIT OF DOWNWARD TRAVEL, MEANS FOR REMOVING LIQUID FROM THE HYDROPHOBIC SURFACE OF SAID DRUM, SAID REMOVING MEANS INCLUDING A SQUEEGEE BLADE MAKING CONTINUOUS CONTACT WITH THE SURFACE OF SAID HYDROPHOBIC PICKUP SURFACE, AND MEANS FOR VARYING THE RATE OF ROTATION OF SAID DRUM. 